FIELD OF INVENTION
The present invention relates to a horizontal, rectilinear type electroplating method and an apparatus for carrying out the same.
Heretofore, a horizontal type plating method was known, by which, however, only one side of a metal strip was plated in an upper side open type plating vessel, and a horizontal plating apparatus for wire materials was also known. However, the known horizontal method and apparatus were confronted with the following serious disadvantages:
The first disadvantage resides in the fact that the replacement of electrode plates used as an anode, and particularly, replacement of a lower side plate, is difficult. Various materials may be selectively used as electrode plates which are used as an anode -- i.e. a zinc anode for galvanization, a nickel anode for nickel plating and a copper anode for a copper plating. During the plating operation these metals are molten and remarkably consumed, which makes it necessary to periodically or semi-continuously replace the anodes. This is particularly true when the plating is being carried out with a large current, as is done in the high speed plating of strips. However, the replacement operation especially during the plating operation is very difficult, when carried out in a horizontal, rectilinear type plating apparatus, because the lower anode is located under the strip to be plated in the apparatus of this type. The upper anode replacement operation is not as difficult as in the case of the lower anode, but is still difficult, when using an upper cover.
A second disadvantage resides in that an anode sludge produced, as a by product of the consumption of the anode process, is deposited on the strip. This leads to defective plating and occurance of pin holes on the strip, whereby the quality of plated products is lowered.
A third disadvantage is that hydrogen gas, which is generated during the plating operation, is stagnated on the surface of the strip, particularly on the lower surface thereof, which leads also to defective plating and occurance of pin holes. Various attempts have heretofore been made to avoid these disadvantages, but no effective method has yet been discovered.